Process of grinding



March 10, 1936. J. E. CASTER ET AL 2,033,324

PROCESS OF GRINDING Original Filed April 1'7, 192

(111102 wag Patented Mar. 10, 1936 UNETED STATES "PATENT c rries John a. Caster, Covington, Ky., and Lester r. Nennin'ger, Cincinnati,

Ohio, assignors, by

' mesne assignments, to Cincinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Original application April 17, 1926, Serial No.

102,765. Divided and this application December 16, 1930, Serial No. 502,752

' 2 Claims. (Cl. 51-278) This invention relates to improvements in the art of grinding and especially to improvements in the art of grinding various portions of a work piece concentric to one another or concentric to a common axis thereof, also to improvements in the art of grinding external surfaces concentric with a previously ground internal bore or hole and to the axis of said hole or bore.

This application is a division of an application entitled Centerless grinder filed April 17, 1926, Serial Number 102,765, which matured into Patent NoT1,791,'713 on FebruarylO, 1931.

In the past, it was customary to mount the work piece between centers to, present same to the action of a grinding wheel or the like,.which centers determined the axis about which the work rotated. This axis may or may not be common to all portions of the work as certain portions of the work may have been ground or. finished about an axis determined by other centers, or the like, which would be slightly eccentric to the axis determined by the present supporting centers. This, of course, would result in the several portions of the work being eccentric to one another, a very slight amount it may be true, but sufilcient to impair the efficient use of the complete article. Also in the past, it was customary to grind or finish the exterior surface of a work piece that was to be subsequently bored and after finishing the external surface supporting the article in a suitable chuck, or the like, by gripping the said exterior surface and proceeding to form the bore or hole about the axis of the supporting chuck and driving means which may or may not be co-axialwith the axis previously utilized for finishing the exterior surface of the work. By the present invention all the above noted difilculties and uncertainties have been eliminated and the work produced has each portion thereof concentric to other portions and has the internal and externalsurfaces of bored workpieces concentric to one another about a given axis. A I u Therefore, one of the principal objects of the present invention is the provision of a novel process of grinding or finishing work pieces having several surfaces that are to be concentric to one another in the finished article. I e

Another object of the invention is the provision of a novel process of grinding or finishing concentric work pieces wherein the succeeding portions of the work'are' ground or finished about an axis determined by the previously conditioned surface so that'concentricit'y of the several por- ..tidns of the work results." Q

A further object of the present invention is the provision of an improved process of grinding or finishing work pieces having various portions thereof concentric to one another and utilizing a centerless grinder for accomplishing the process.

Other objects and advantages of the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawing-illustrating the several steps of the process and the mode by which they are accomplished and it is to be understood that any modifications may be made in the exact order of the steps of the process, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

In the drawing:

Figure 1 is a diagrammatic representation of a centerless grinder for finishing certain portions of a work piece and determining the axis thereof.

Figure 2 is a further step in the process diagrammatically illustrating the finshing of an intermediate portion of the work piece shown in Figure 1 concentric to the axis previously determined.

Figure 3 is a diagrammatic representation of the finishing or forming of an internahbore in a work piece and its axis of rotation.

Figure 4 is a diagrammatic representation of the forming of the outer surface of the work piece shown in Figure 3 concentric with the axis of the work piece as determined in Figure 3.-

Figure 5 is a fragmentary elevational view of the essential elements of a centerless grinder for performing the process of this invention.

As was suggested above it is proposed to-perform the novel process of this invention by a centerless grinder which, as is well known, comprises opposed grinding and regulating wheels forming a grinding throat 'therebetween in which the workpiece'is placed during the grinding operation. -In Figure 5 these'elem'ents are shown in operative relation in which the numeral l0 indicates the grinding wheel and u the regulating wheel forming therebetween the grindw ing throat in which a work piece isplaced being peripherally supported by a work rest blade I! which subtends thegrinding throat. The upper surface of the blade I2 is incline'dtoward the regulating wheel, as shown at i3, and the positioned;

i in the case of sleeves or bushings in which the exterior surface must be .concentric wlth the inner-bore or in various shaft and spindle structures having portions of different diameters, all of which must be concentric. The particular work pieces chosen for purpose of illustration are a shaft or the like having a multiplicity of diameters or portions and a sleeve or bushing member. Prior to the present invention difllculty has been experienced in grinding work pieces of this nature, due to the trouble in properly centering, supporting and rotating the shaft member after the completion-thereof of certain portions and to the inability to properly rotate hollow work pieces, such as bushings, about the predetermined axis of the hole or bore therein.

To overcome these difliculties the present machine embodies certain means for limiting the movement of the predetermined work axis in the direction of the grinding wheel, in conjunction with means which will continuously urge the work toward the grinding wheel, but willbe capable of yielding as to eccentric portions of the work, for example, to prevent jam or breakage during the grinding.

As shown in Figure 1 the work piece 15 is mounted in the throat of the centerless grinder comprising a pair of grinding wheels Ilia op-' posed to a pair of regulating wheels Ila between which is 'the work rest blade I241. contacting with the projecting portions H of the work for freely or floatingly supporting said work piece while the said terminal portions thereof are being ground or finished and the axis of the work piece determined. As is well known the grinding wheel of a centerless grinder removes stock from the work, the rotation of which work is frictionally controlled by the regulating wheel. The regulating wheels a are illustrated having their axes disposed at an angle to the axis of the work whereby a feeding thrust component is exerted on the work tending to feed the same toward the right, as seen in Figure 1. The work rest-blade l2a supports an adjustable stop l6 limiting the feeding movement of the work.

After the work piece has been completed, as shown in Figure 1, it is passed to the mechanism shown in Figure 2 for grinding the central enlarged portion I! of the work piece l5. This machine is a centerless grinder and comprises a grinding wheel lob in opposition to a regulating wheel llb having a. work rest blade |2b therebetween. The work piece I5 is now peripherally supported byengaging the periphery of the enlarged portion ll of the work IS. The regulating wheel llb, similar to regulating wheel Ha, has its axis disposed obliquely to the axis of the work for effecting a feeding component thereon against the stop l6 carried by the blade l2b. To feed the work into thegrinding. wheel the regulating wheel is supported by a slide l8 movable by any; suitable or desirable means toward the grinding wheel and as shown in Figure 2, by a spring or the like IS. A second slide.

20 forms an abutment for the spring l9 and forms a means whereby the slide l8 and regulating wheel may be moved as a unit with the spring l9. The axial approach of the work I5 and grinding wheel lob is limited by the engagement of contact rollers or the like 2| supported by an arm 22 and engaging with the previously formed surface M of, the work l5.

In the use of the present machine the work to be ground is introduced into the grinding throat between the grinding and regulating wheels Hlb andi lb when the latter are in a separated position, the work resting on the upper inclined face of the work rest blade l2b and being urged by gravity in the direction of the regulating wheel. The regulating wheel is then moved inward urging the work piece toward the grinding wheel. At the same time the grinding wheel is rotated at a high or grinding rate of speed and with its operative surface adjacent the work rest blade moving downward. As the wheels are brought toward each'other the work piece will be rotated by the regulating wheel and its surface removed to the extent which the regulating wheel urges it in the direction of the grinding wheel through the cutting action of said latter wheel. If there were no means for limiting the movement of the work in the direction of the grinding wheel, the work piece would naturally round up and establish its final center or axis through a substantially uniform peripheral reducing action. It is frequently the case however, when the second surface is to be ground concentric with the previously finished surface to within limits of one or two ten thousandths of an inch that the second surfaces are not originally concentric. The work cannot, therefore, be allowed to float within the grinding throat in the usual manner. The rollers 2| are, therefore, adjusted as to engage the projecting terminal portions ll when any point on the enlarged portion I! has been cut down to the prescribed radius length from the said surfaces of the projecting portions I4. This means that the movement of the work-piece toward the grinding wheel is, therefore, limited by inter-engagement'of the projecting portions of the work and rollers for this particular point, so that if the work is eccentric along that particular diameter Y and its approach toward the grinding wheel is limited, it will project to the extent of its eccentricity in the direction of the regulating wheel. In ordinary centerless grinding the regulating wheel is formed from a hard, unyielding material, usually suitably bonded abrasives and is similarly unyieldingly supported which will positively force the work toward the grinding wheel. In the present instance, however, due to the limitation of movement of the work in one direction, it is impossible to utilize such a rigid regulating wheel and mounting. On the contrary, use is made of the resilient or yielding device, such as the spring 19 on the slide 20 so that it accommo .dates itself to irregularities in the radial size of the work piece in the direction of the regulating wheel and jamming of the parts will be prevented. It will be understood that instead of providing the spring or yielding device IS the wheel itself may be made of yielding material, such as rubber or other substance and it will be understood that the said yielding device or spring I9 need'not be necessarily mounted at the particular point shown in the drawing but may be anywhere in the train from the initial source of power for actuating the supportingslides to the face of the wheel itself. The foregoing description clearly deflnes the process of grinding the external surface of various portions of the work concentric to a predetermined axis man to all portions thereof.

The limiting rollers 2| and arm 22 are illustrated in elevation in Figure 5 which shows the relation of the said arm and rollers to the other parts of the mechanism. As shown therein the arm 22 may be pivotally mounted at 23 to any suitable or desirable support and adjusting mechanism may be provided for adjusting the position of the arm for various kinds, types and sizes of work, all as illustrated and fully described in the parent application, above referred to.

Figures 3 and 4 illustrate the steps of the process for concentrically grinding or finishing internal and external surfaces. As there shown a work piece 24 is mounted in a chuck 25 to have its inner surface 26 suitably ground or finished by the small diameter or internal grinding wheel 21,. After this bore has been formed the work 24 is mounted, as shown in Figure 4, on a previously ground or finished mandrel, arbor, or the like 28 and placed between opposed grinding and regulating wheels, such as those shown in Figure 2, whereupon the process again takes place and the work 24 is reduced until the protruding ends of the mandrel 2B, which represent extensions of the interior surface of the bore, engage the limiting rollers 2| as described in connection with Figure 2, whereupon the work is concentric to the axis of the mandrel 28 which is concentric to the axis of the bore or surface 26 whereby the inner and outer surfaces are concentric to one another. It is to be understood that the work rest blade contacts with the outer surface of the work 24 when same is being reduced, as previously described.

From the foregoing description taken in connection with the'drawing, it will, therefore, be apparent that the work piece may be readily mounted on a supporting arbor properly fitting in the interior thereof and the device as a unit loosely placed within the grinding throat with the work piece itself, in contact with the work supporting blade and surface of the regulating wheel. The regulating wheel is then brought inward, urging the work piece in the direction of the grinding wheel, the movement of the surface of the work piece in that direction being limited by interengagement of the idler rollers 2| and the projecting ends of the arbor, so that it is impossible for the work to be ground below determined size or to be ground to any circle except one concentric with its inner diameter;

also, that during this operation the regulating piece on an arbor or the like, floating said work piece and arbor on a work rest blade in the throat of a centerless grinder between opposed grinding and regulating wheels, yieldingly shifting the .work and arbor toward the grinding wheel, and

limiting said movement by engaging the surface of the arbor representative of the surface of the internal bore or hole.

2. The process of producing work pieces having an interior and an exterior surface concentric with one another, consisting in forming the interior surface in the work piece by any known process and thereby determining the axis of the work as a whole, mounting said work piece on an arbor and floating said work and arbor in the throat of a, centerless grinder consisting of opposed grinding and regulating wheels, yieldingly feeding the grinding wheel and work toward one another while the rotation of the work and arbor are being controlled by the regulating wheel, and subsequently stopping the relative shifting of work and wheel by engaging the arbor representation of the surface of the interior bore in the work and utilizing same as a determinant of the ultimate size and axis of the work.

JOHN E. CASTER. LESTER F. NENNINGER. 

